Mod that keeps the cooling fans on when the AC is on ***Split***

[Ron]

Since you were considering jumping the relays and having the fan run when it's on 4th speed (always for you...), consider using a fuse to jump the Otterstat -- The fans would run whenever the ignition was on, but it's non-intrusive, Plug-N-Play...

[DMC-81]

If the problem statement is "prevent the cooling fans from cycling with the A/C compressor (i.e. they are on any time the A/C is on, regardless of the compressor cycle)"' another plug and play alternative is the Solid State Fan Relay from Dave McKeen. From his website it "Delays fans for one second and keeps fan running for 20 seconds minimum. That eliminates fans cycling when AC cycles. Plug and Play."

I have that unit and his Solid State Fan Fail unit. These 2 parts are a great upgrade, as are his other offerings.

[Ron]

That would do the trick...and no "buts"!

[Josh]

why do you want to do this?
Seems like you have cooling system problems you are trying to mask

[DMCMW Dave]

The way the electrical system is set up the fans and the A/C MUST cycle. If you set up the A/C or the fans to run continuously you will overload the electrical system.

I wired my personal car like this in about 1998, actually using Darryl's instruction. Still no overloads, no melted wiring, etc. I do maintain the connections. I was likewise tired of feeling the fans come on and off with the compressor. My car has aftermarket high power fans (not the modern low-current ones, but from another European car circa 1995). I see no detriment. Having the fans cycle on and off doesn't really prevent any overloads, in fact a constant current rather than repeating the startup current over and over seems beneficial. My own observations, YMMV.

[CFI]

Is there anyway to prevent the fans from coming on when AC is on?

[Bitsyncmaster]

Is there anyway to prevent the fans from coming on when AC is on?

Pull the diode that has the pink wire on it. No fans when the AC is on will probably blow an AC hose.

[CFI]

Pull the diode that has the pink wire on it. No fans when the AC is on will probably blow an AC hose.

Why would it blow a hose?

[FABombjoy]

Not all cars have a high pressure cutoff switch or relief valve.

If you have a car with no HP switch (and consequently no high pressure relief valve), and the compressor never shuts off, and the condenser can't eliminate enough heat for the low side to function properly, all that energy has to go somewhere.

[Bitsyncmaster]

Not all cars have a high pressure cutoff switch or relief valve.

If you have a car with no HP switch (and consequently no high pressure relief valve), and the compressor never shuts off, and the condenser can't eliminate enough heat for the low side to function properly, all that energy has to go somewhere.

+1
With no fans running and the AC on the high pressure goes really high.